Field of the Invention
Embodiments of the present invention generally relate to an RF choke and gas feed tube for matching impedance in a plasma processing apparatus.
Description of the Related Art
As demand for larger flat panel displays continues to increase, so must the size of the substrate and hence, the processing chamber. As solar panel demand increases, higher RF field is sometimes necessary. One method for depositing material onto a substrate for flat panel displays or solar panels is plasma enhanced chemical vapor deposition (PECVD). In PECVD, process gases may be introduced into the process chamber through a showerhead and ignited into a plasma by an RF field applied to the showerhead. As substrate sizes increase, the RF field applied to the showerhead may also correspondingly increase. With the increase in RF field, the possibility of premature gas breakdown prior to the gas passing through the showerhead increases as does the possibility of parasitic plasma formation above the showerhead.
Therefore, there is a need in the art for an RF choke and gas feed through to reduce premature gas breakdown and parasitic plasma formation.